Chapter 5: Gases

Question 1

Barometer

Answer 1

A device for measuring atmospheric pressure

Question 2

Manometer

Answer 2

A device for measuring the pressure of a gas in a container

Question 3

BIG WHOPPER

Answer 3

1 atm = 760 mmHg = 29.92 inHg = 760 torr = 101325 Pa = 101.325 kPa = 14.69 psi

Question 4

Boyle’s Law

Answer 4

PV = k
P1V1 = P2V2
Inverse relationship between pressure and volume

Question 5

Charles’s Law

Answer 5

V = bT
V1/T1 = V2/T2
Direct relationship between temperature and volume

Question 6

Avogadro’s Law

Answer 6

V = an
V1/n1 = V2/n2
Direct relationship between number of moles and volume

Question 7

Universal gas constant

Answer 7

0.08206 L atm / K mol

Question 8

Ideal gas law

Answer 8

PV = nRT

Question 9

Molar volume of an ideal gas at 273 K and 1 atm

Answer 9

22.4 L

Question 10

Standard temperature and pressure (STP)

Answer 10

0 degrees Celsius & 1 atm

Question 11

Molar mass of a gas

Answer 11

dRT/P

Question 12

Gas density unit

Answer 12

Grams per liter

Question 13

Dalton’s Law of Partial Pressures

Answer 13

For a mixture of gases in a container, the total pressure exerted is the sum of the pressures that each gas would exert if it were alone.

Question 14

Partial pressure

Answer 14

The pressure that a particular gas would exert if it were alone in the container

Question 15

Mole fraction

Answer 15

The ratio of the number of moles of a given component in a mixture to the total number of moles in the mixture
x1 = n1/nTOTAL = P1/PTOTAL

Question 16

Postulates of the Kinetic Molecular Theory

Answer 16

1. The particles are so small compared with the distances between them that the volume of the individual particles can be assumed to be negligible (zero).
2. The particles are in constant motion. The collisions of the particles with the walls of the container are the cause of the pressure exerted by the gas.
3. The particles are assumed to exert no forces on each other; they are assumed neither to attract nor to repel each other.
4. The average kinetic energy of a collection of gas particles is assumed to be directly proportional to the Kelvin temperature of the gas.

Question 17

Root Mean Square Velocity

Answer 17

√3RT/M
R = 8.3145 J/K mol (J = joule = kg m^2/s^2)
T = temperature of gas (in K)
M = mass of a mole of gas in kg
Final units are in m/s.

Question 18

Diffusion

Answer 18

Mixing of gases

Question 19

Effusion

Answer 19

The passage of a gas through a tiny orifice into an evacuated chamber

Question 20

Graham’s Law of Effusion

Answer 20

Rate of effusion for gas 1/Rate of effusion for gas 2 =

√M2/√M1

Question 21

We must correct for non-ideal gas behavior when:

Answer 21

1. The pressure of the gas is high.

2. The temperature is low.

Question 22

Under the conditions of real gases:

Answer 22

1. Concentration of gas particles is high.

2. Attractive forces become important.

Question 23

Van der Waals Equation

Answer 23

[Pobs + a(n/V)^2] x (V-nb) = nRT

Question 24

For a real gas the _________ is lower than __________.

Answer 24

Actual observed pressure; the ideal pressure